Placebo: 32 participants took the same amount of placebo capsules, containing a cellulose powder.

The chitosan was of fungal origin and was taken 15 minutes before meals. Previous research suggests that it may take some time for chitosan to dissolve in the digestive system before becoming usable (4).

At the start, middle and end of the study, the researchers measured body weight, body composition, the blood lipid profile and glycated hemoglobin (HbA1c).

A total of 86 participants completed the study, or 90% of those who initially started.

Bottom Line: This was a randomized controlled trial examining the effectiveness of the weight loss supplement chitosan.

Finding 1: Chitosan Led to Weight Loss

Supplementing with chitosan led to significantly more weight loss than the placebo.

In fact, those who took chitosan lost 2.2 lbs (1.0 kg) each month, on average. This amounted to 6.8 lbs (3.1 kg) over the 3-month study period.

In comparison, the placebo group did not experience significant weight loss.

This weight loss in the supplement group was caused by loss of fat mass and lean mass, as shown in the chart below.

Similarly, waist and hip circumference decreased among the participants in the supplement group.

These findings are interesting, because the participants did not go on a diet or increase their physical activity. The chitosan, on its own, had significant benefits.

Previous trials do not support these results. Without other weight loss strategies, chitosan supplements have not lead to significant weight loss (6, 7).

However, chitosan may be effective when participants are also making dietary, exercise or behavior modifications (9, 11, 12).

Bottom Line: Supplementing with chitosan led to significant weight loss without any dietary restrictions or increased exercise.

Finding 2: Chitosan Improved Blood Sugar Control

HbA1c is also known as glycated hemoglobin. It is measured to evaluate the average blood sugar levels of the past few weeks.

In the present study, supplementing with chitosan led to a reduction of HbA1c levels in participants who had high levels (over 6%) initially.

These results are supported by a previous study showing that chitosan may reduce blood sugar after meals in humans (13).